1. Field of the Invention
This invention relates to cameras for daylight and flash photography, and more particularly to an automatic exposure control system for such cameras which is switched to either the daylight and flash mode depending upon whether or not a storage capacitor across which is connected a flash tube is sufficiently charged. Still more particularly, it relates to a novel operating mode selection device which enables the system to operate while insuring that the daylight and flash exposure control factors are not mixed with each other during each exposure operation despite the fact that the voltage on a storage capacitor has increased up to or fallen below a normal firing level during that exposure operation.
2. Description of the Prior Art
Some of the conventional automatic exposure control systems for daylight and flash photography have a problem that an unintentional actuation of the operating mode selection switch tends to occur at a point in time during an exposure operation in either the daylight or flash mode so that photographic information is changed with failure of the correct exposure. Particularly with the system for a camera of the type which is switched from the daylight to the flash mode in automatic response to the attainment of the voltage on a storage capacitor to a sufficient or normal firing voltage level for a flash tube, when this attainment occurs at a point in time during an exposure operation, there results the situation where one of the exposure aperture and time controls is made in the daylight mode, while the other is in the flash mode, thereby no correct exposure can be obtained. Further, there is some possiblity of accidental occurrence of firing of the flash tube during the daylight exposure operation which results in partial flash exposure, or so-called slit exposure, as the incident film frame is exposed to a complex of daylight and flash light at a portion of the entire area thereof, the other portion of which is exposed to only the daylight.
An object of the present invention is to provide an automatic exposure control system for a camera of flash photographic capability which has overcome the above mentioned conventional drawbacks and which operates in such a manner that when either the automatic daylight or flash mode is in operation, it is made impossible to effect automatic selection of the other mode until that one frame exposure or that continuous succession of frame exposures has been completed, thereby the reliability exposure control in either of the daylight or flash made is greatly improved.
Another object is to provide an automatic exposure control system which is switched from the daylight mode to the flash mode in automatic response to the attainment of the voltage on a storage capacitor reaching a normal firing level for a flash tube connected across the capacitor, characterized in that when the normal firing voltage appears both on a voltage detector and across the flash tube at a point in time during a daylight exposure operation, the switching from the daylight to the flash mode which may be followed by the firing of the flash tube can be prevented from occurring.
Still another object is to provide an automatic exposure control system which operates in such a manner that, as a continuous succession of frame exposures are made by use of a motor drive unit associated with the camera, when the attainment of the voltage on the storage capacitor to the normal firing level occurs at an intermediate point in time during the continuous succession of frame exposure operations, at least that one of the frames which is coincident with that intermediate time point is caused to be subjected to a daylight exposure operation and at least that one which is next thereto is caused to be subjected to a flash exposure operation.
These and other objects and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which: